Switch to edit mode using the briefcase icon
Click the circle "deck token" to show the menu
In the menu, select "Add/Remove Cards" to show the deck popup
From here, you can add multiple copies of cards, remove cards, and add jokers
Watch the video at the bottom of this page for a visual tutorial.
Jokers can be added and removed by following the instructions above to show the popup, then clicking the + and - buttons next to the joker cards. By default, cards are available for red and black jokers but with 0 cards added.
To create a "mega-deck" with multiple decks combined, follow the instructions above to show the popup, then simply add multiple copies of every card. Use the "All +1" button to quickly add an additional copy of every available card.
If you'd like multiple separate card decks, click a deck in the bottom popup to add an additional deck token. Read more about custom card decks
Cards can be removed from the deck to create a stripped deck. Cards can be added and removed by following the instructions above to show the popup, then clicking the + and - buttons next to each card.